1. Field of the Invention
The present invention relates to a radio communication apparatus configured to perform radio communication with radio-frequency identification (RFID) transponders or the like.
2. Description of the Related Art
In recent years, much attention has been paid to transponders from and to which data can be read and written by radio. Each transponder stores an ID specific to it. The transponder may be attached to an article, enabling the article to be identified in non-contact fashion. The transponder is generally called an RFID tag, RF tag, radio tag or the like. A radio communication apparatus that accomplishes radio communication with the transponder is called a reader-writer, an interrogator or the like.
Jpn. Pat. Appln. KOKAI Publication No. 2003-150914 discloses a radio communication apparatus that comprises an antenna and a transponder-supplying mechanism. The transponder-supplying mechanism supplies transponders, one after another, to a region to which a radio signal can propagate. The antenna emits and picks up radio signals to and from the transponders. Thus, the radio communication apparatus can read data stored in each transponder. The radio communication apparatus can also write data to each transponder.
The conventional transponder can store data, word by word. One word is two-byte data. Hence, the process of writing data must be repeated seven times in order to store 14-byte data in the transponder. If errors occur while the data is being written to the transponder, the radio communication apparatus needs to perform the data writing again, from the first step thereof. That is, the apparatus must start the data writing again, with the step of detecting the transponder.
Writing errors are liable to occur in any type of radio communication apparatus that writes data to transponders that are moving, like the radio apparatus disclosed in the above-identified publication. This is because the distance between the antenna of the apparatus and the transponder changes from time to time. Once a writing error has been made, the radio communication apparatus starts the data-writing process again. Inevitably, the radio communication apparatus of this type has low process efficiency.